Pus for Culture and Sensitivity

Pus for Culture and Sensitivity, Anaerobic Wound Culture. A bacterial wound culture is a test that detects and identifies bacteria that cause infections (pathogenic) in a wound. Any wound may become infected with a variety of bacteria. A culture helps to determine whether a wound has become infected, which type(s) of bacteria are causing the infection, and which antibiotic would best treat the infection and help heal the wound.

Wounds may be superficial breaks in the skin such as scrapes, cuts, and scratches, or may involve deeper tissues such as incisions, bites, punctures, or burns. (Read the article on Wound and Skin Infections.)Collecting a sample of fluid, cells, or tissue from the wound and placing it on or in appropriate nutrient media performs a culture. The media encourages the growth of bacteria that may be present, allowing for further testing and identification.

Pus for Culture and Sensitivity?

Typically, only one kind of pathogenic bacteria is causing the infection in a wound. However, there may be several types of normal skin bacteria present in the culture. Separating the various types of bacteria and identifying the pathogenic bacteria requires one or more days to perform.

Performing a Gram stain usually helps healthcare practitioners determine the type of bacteria present and provide rapid results. Determining the cause of infection greatly reduces the need for other tests by considering the shape and color (morphology and staining characteristics).

Because the stain results read under the microscope are not definitive, further tests such as biochemical reactions or mass spectrometry must be performed to identify the bacteria. Mass spectrometry using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) can provide identification to the genus and species level in less than an hour after the bacterial colony grows on the culture media.
This technique significantly decreases the time needed to identify bacteria from traditional biochemical reactions that require overnight incubation.

For many of the pathogens identified in wound cultures, testing is done to determine which antibiotics will be effective in inhibiting the growth of the bacteria (see Antibiotic Susceptibility Testing). The Gram stain of the wound, the culture, and susceptibility testing all contribute to informing the healthcare practitioner which pathogen(s) are present and what antibiotic therapy is likely to inhibit their growth.

Why is Pus for Culture and Sensitivity analysis done?

Many bacteria are resistant to common antibiotics. This means that the drug can’t kill the bacteria. Sensitivity analysis is a useful tool to help quickly determine if bacteria are resistant to certain drugs.

Examples of antibiotic-resistant infections include:

• a persistent sore throat
• a recurring urinary tract infection (UTI)
• an unresponsive case of pneumonia

Sensitivity analysis may be ordered if your infection doesn’t respond to treatment.

This can help your doctor to see if the bacteria that’s causing your infection has developed resistance. Your doctor can then determine which drug would be more effective in treating the infection.

How is sensitivity analysis performed?

Sensitivity analysis starts with a bacterial sample. Your doctor will get this sample by sampling the infected area. Your doctor can sample any area that has an infection.

We may take samples from:

• blood
• urine
• sputum (spit)
• inside the cervix
• a pus-containing wound

Your doctor will send the sample to a laboratory, where it’ll be spread on a special growing surface. The grown bacteria is known as a culture, and bacteria in the culture will grow and multiply.

The bacteria will form colonies, or large groups of bacteria, that will each be exposed to different antibiotics.

These colonies can be susceptible, resistant, or intermediate in response to the antibiotics:

• Susceptible

   means they can’t grow if the drug is present. This means the antibiotic is effective against the bacteria.

• Resistant

   means the bacteria can grow even if the drug is present. This is a sign of an ineffective antibiotic.

• Intermediate

  To prevent growth, we need a higher dose of the antibiotic.

Why Get Tested?

To detect and identify the bacteria causing an infection of your wound and to help guide treatantibioticment of your wound infection

When should you get tested?

When you have signs and symptoms of wound infection, such as a wound that is tender, red, swollen, draining fluid or pus, and slow to heal

Sample Required?

A sterile swab can collect cells or pus from a superficial wound site. From deeper wounds, aspiration of fluid into a syringe and/or a tissue biopsy are the optimal specimens to allow for the recovery of aerobic and anaerobic bacteria.

How do we use it?

Healthcare providers use a bacterial wound culture, along with a Gram stain and other tests, to determine if a wound is infected and to identify the bacteria causing the infection.

Perform susceptibility testing to identify which antibiotic can stop the growth of the bacteria causing the infection when a culture indicates that a wound is infected. They typically carry out this testing automatically when collecting the wound specimen, allowing for prompt guidance on appropriate therapy based on antimicrobial susceptibility results.

A wound culture may also sometimes be ordered for an individual who has undergone treatment for a wound infection to determine whether the treatment was effective. It may also be ordered at intervals for a person who has a chronic infection to help guide further treatment.

If a fungal infection is suspected, then a fungal culture of the wound specimen may be ordered along with the bacterial wound culture. Yeast and some fungi may grow on the same media as bacteria, but many fungi are slow-growing. The media used to recover fungi inhibits bacterial growth and supports fungal growth for several weeks.

What are the results of a sensitivity analysis?

After growing and testing the bacterial cultures with antibiotics, your doctor can analyze the results. These results can help determine the best antibiotic to treat your infection.

Susceptible

Your doctor will typically select an appropriate drug from the report listing it as “susceptible,” indicating it can combat the bacteria. (Active voice, slightly shortened)

Intermediate

If there are no known drugs available in the susceptible group, doctors will prescribe a drug from the “intermediate” group.

You’ll likely have to take a higher dosage for a longer period if you’re taking a drug from the intermediate group. You may also experience medication side effects.

Resistant

If bacteria have shown resistance to an antibiotic, you shouldn’t use it to treat your infection. Your doctor will determine the best drug if multiple antibiotics can effectively kill the microorganism causing your infection.

Doctors may prescribe a combination of antibiotics to treat an infection caused by bacteria that are resistant to the usual drugs. This combination aims to work together in fighting the bacteria.

Using active voice, the drugs in this category could greatly reduce costs and may require administering intravenously through a needle in your vein. You’ll also likely have to take a combination of drugs for an extended period.

Further testing

Doctors may need to conduct further testing for some infections because the drugs normally used to treat the bacteria or fungi causing the infection are not always effective. It is also possible that the sample taken from the infection may contain more than one microorganism. Susceptibility testing can help determine which antibiotic or combination of antibiotics will be most effective in treating the different types of bacteria causing the infection.